[jimcolt]

I have never heard of plasma increasing the thickness of the plate edge. Edge squareness with the plasma system can be relatively square...or can be quite tapered depending on the Plasma system (there are low end air plasma systems that cost $500, and there are high performance oxygen plasma systems that cost $45,000...the cut quality, tolerance and metalurgical side effects are better with the high end industrial systems!), the cnc machine's motion capability in terms of cut path accuracy and acceleration rates, the torch height control systems ability to pierce and cut at the proper heights, and the part program.

Edge squareness can be less than 1 degree on many materials using the right plasma cutting equipment.

The sample in the picture is 3/8" carbon steel cut with a Hypertherm HPR130 high performance plasma with oxygen as the plasma gas and air as the shield....it is cut at 80 Amps at 75 inches per minute. The hole (that is tapped) was 5/16 diameter...and was tapped with a standard ($3.00) Craftsmen brand tap to demonstrate that there is minimal hardening of the edge with this process. You could not tap the hole if the part was cut with an air plasma!

Jim Colt